The Research On The Devices And Methods For The Elimination Of Vortex In The System Of Two Hydrocyclones Connected In Series

Hydrocyclone is widely used in the industrial areas, such as the coaldressing, chemical industry, environmental protection and so on, due to itssimple structure, convenient operation, saving place, durability and easymaintenance.Sometimes,in order to meet the need of industrial production or toachieve some specific purposes,hydrocyclones need to be combined together,such as the series connection, parallel connection and so on. If the overflowproducts of one production still need to be classified, another hydrocylone needsto be connected to the overflow of the original hydrocylone and this is usuallycalled “the system of two hydrocyclones connected in series”. The real problemexists in the system of two hydrocyclones connected in series is that theoverflow of the first hydrocycone usually is highly swirling flow and littleresearch have been done on how this highly swirling flow effecting theperformance of the second hydrocyclone.As the system of two hydrocyclonesconnected in series is widely used in many industrial plants, the research on howthe highly swirling inlet flow effecting the performance of hydrocyclone andhow to eliminate the vortex in the overflow of the first hydrocyclone so as topromote the performance of the second hydrocyclone and the whole system isvery necessary.This research first used particular devices(two separating hydrocycloneswith different inlet parameters) were used to produce two overflows of differentvortex intensity and they were used as the inlet flows of the classifyinghydrocyclone.Together with the case of steady inlet flow, the performances ofthe classifying hydrocyclone under three inlet flows with different vortexintensity were achieved. Through comparison, the result shows that the performance of the hydrocyclone decreases with the increase of vortex intensityof the inlet flow.After making sense of the relationship between the vortex intensity of theinlet flow and the classification performance of the classifying hydrocyclone,inorder to eliminate the vortex in the overflow of the first hydrocyclone and topromote the performance of the classifying hydrocyclone and the whole system,a crossblade was installed in the connecting pipe between twohydrocyclones.The results of the experiments showed that, the vortex inoverflow of the separating hydrocyclone was eliminated effectively and theclassification performance of the classifying hydrocyclone was highlyimproved.However,at the same time, the crossblade can also produce a lot ofresistance to the overflow and lead the underflow yield of the separatinghydrocyclone to increase.Due to the big resistance of the crossblade,a new spiritual crossblade wasdesigned. The results of experiments shows that, comparing with thecrossblade,the spiritual crossblade can also eliminate the vortex effectively withlower resistance to the overflow. It is unavoidable to produce resistance whenusing blade to eliminate the vortex.However,considering the lower resistance ofspiritual crossblade,through the reorganization of the separating hydrocyclone,itis feasible to improve the performance of the whole system under the conditionof keeping the underflow yield of the separating hydrocyclone unchanged.In view of the fact that crossblade can effectively eliminate the vortex andimprove the performance of the classifying hydrocyclone,it is applied to thesytem of two separating hydrocyclones connected in series. The results showsthat,after eliminating the vortex of the first separating hydrocyclone,theseparation performance of the second separating hydrocyclone is highlyimproved. This suggests that it is also feasible to improve the performance of thewhole system of two separating hydrocyclones connected in series through theblades designed. Simultanously,CFD simulation was conducted to model the the effect ofthe inlet flow vortex intensity on the classification performance of theclassifying hydrocyclone and the effect of eliminating vortex with differentblades. The results of simulation shows that, the significant decrease of thetangential velocity and the unsteadibility of the flow field are the main reasonsfor the deterioration of the performance of the classifying hydrocyclone,whilethe intensification of the downwelling due to the resistance of the blade is themain reason for the underflow yield increase of the first separatinghydrocyclone.The results of the simulation confirm and explain the results of theexperiments well.